Hmm that's a tough one, I don't know how to judge that. I guess it's either white, black and then all shades of grey cover 3 colors or just 1. I don't know if it's "correct" but I would lean towards counting them all as 1, otherwise 4 colors would be quite limiting when using white/black/grey as part of it.
If anyone else has any feedback, please let me know!
I think you're taking it to another degree. That would be like saying, Red, Yellow and Blue are colours and everything else is a shade because they make up from the three primary colours being mixed. The definition of shade is not what you've defined so I'm not sure how you arrived at orange being a shade of red. I don't think the definition of colours is in dispute. As Mana said, Red and shades of red, ie; dark red, or light red are considered shades of red.
Just ripped this from Google -
Not sure how useful this is with aligning what you had in mind but it's some food for thought!
Well the thing is that colour is usually a representation of the primaries, blue, yellow and red. Black and white are unnatural 'colours' which is why most artists don't use either, and often to represent black or a dark area using a very dark blue, dark purple etc. Which is why often people refer to black and white as shades not colours.
In pixel art it is common to have a highlight area around the pixel art which is represented by black. So you can see the problem if the definition of colour isn't specific in this case. I think science isn't a helpful tool in this situation because we don't live in a reality of pure absence of light. We always have a degree of light.
